Some polymer applications call for a high degree of stiffness (high flexural modulus). Examples include some film applications such as photographic film base and packaging material. One approach to obtain such stiff materials is to add fillers such as carbon or silica, or to incorporate fibers, such as glass and carbon fibers into a relatively flexible polymer, thereby forming a composite material. Unfortunately, composites are difficult to repair and recycle. These and other drawbacks can make composites unsuitable in a number of applications.
Polymers of carbon monoxide and ethylenically unsaturated hydrocarbons commonly referred to as aliphatic alternating polyketones (hereafter, "polyketones") are now well known. High molecular weight alternating aliphatic polyketones are of considerable interest because they exhibit a good overall set of physical and chemical properties. This class of polymers is disclosed in numerous U.S. patents assigned to Shell Oil Company exemplified by U.S. Pat. Nos. 4,880,903 and 4,880,904 which are incorporated herein by reference.
Stiffening polyketones has previously been attained through the formation of composites with the addition of materials such as various glasses and fibers. U.S. Patent No. 5,122,564 provides an example of this approach of the prior art. Stiffening polyketones without necessarily resorting to composite formations would help expand the range of applications for polyketones.